It is well known in passive seat belt systems to mount a seat belt retractor on the door so that outward swinging movement of the door will automatically move the restraint belt outwardly and forwardly with respect to the occupant seat in order to facilitate occupant ingress and egress. When the door is swung to the closed position, the belt is rewound on the retractor and thereby restored to a taut restraining condition about the seated occupant.
The prior art has recognized that a rapid opening movement of the door may induce an acceleration in excess of the 0.7 g's locking sensitivity which is mandated by Federal Motor Vehicle Safety Standard No. 208. If the seat belt retractor locks up during opening movement of the door, the door cannot be opened any further because the restraint belt is prevented from further unwinding from the retractor.
Thus, the prior art has proposed several devices which will actively prevent the retractor from locking up during a rapid door opening movement.
For example, Arlauskas U.S. Pat. Nos. 3,692,328, Fancy 3,694,002 and Augunas 3,727,943 teach the provision of a disablement mechanism between a door latch and a seat belt retractor to release the lock bar of the retractor from engagement with the reel and to block any subsequent locking of the lock bar when either the inside or outside door handle is actuated. This disablement is maintained, even if the door handles are released, as long as the door latch is unlatched.
Another approach to disabling a door mounted seat belt retractor is provided in Giffen U.S. Pat. No. 4,040,645 in which a plunger extends downwardly from the door mounted retractor and interacts with a ramp mounted on the door sill. Whenever the door is open, the plunger is extended and maintains the lock bar of the retractor in its unlocked position.
It would be desirable to provide a device for controlling the lock up of a door mounted inertia retractor without the addition of the added mechanisms required by the above-described prior art.